Modeling the Asymmetric Diels–Alder Reaction: Using a Combination Wet Lab/ Computer Lab Approach to Examining Organic Reactions

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 1 Issue 5 (1996), S1430-4171(96)05067-4

Modeling the Asymmetric Diels–Alder Reaction: Using a Combination Wet Lab/ Computer Lab Approach to Examining Organic Reactions

Brent Steadman, Moses Lee and T. W. Hanks*

Department of Chemistry, Furman University, Greenville, SC 29613

Published online: 12 December 1996

Abstract. Molecular modeling is rapidly becoming a standard analysis tool for the synthetic chemist. It is appropriate that students be exposed to modeling in conjunction with wet chemistry and instrumental analysis. The Diels–Alder reaction between cyclopentadiene and l-menthyl acrylate leads to the production of four diastereomers. Both the endo/exo ratio and (R/S) ratio (referring to the stereochemistry of the newly generated stereocenter at the ring 2 position) are dependent upon reaction conditions. Simple examination of the calculated geometries and frontier orbitals of the starting reagents offers explanations for the observed selectivities. More detailed modeling of the transition states leading to the various products suggests that the cyclization reaction is asychronous and gives insight into the relative importance of molecular features on the energies of the available reaction pathways. This exercise lets undergraduates investigate a problem of current chemical interest. As in a research project, they are required not only to think about the chemistry being investigated, but to also examine the assumptions and limitations of their analysis tools.

Key Words: Laboratories and Demonstrations; Diels-Alder; molecular modeling; Mopac; education; molecular mechanics

(*) Corresponding author. (E-mail: hanks@furman.edu)

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